Advances in polymerization and catalysis have resulted in the ability to produce many new polymers having improved physical and chemical properties useful in a wide variety of superior products and applications. With the development of new catalysts, the choice of polymerization techniques (solution, slurry, high pressure or gas phase) for producing a particular polymer have been greatly expanded. Also, advances in polymerization technology have provided more efficient, highly productive and economically enhanced processes.
As with any new technology field, particularly in the polyolefins industry, a small savings in cost often determines whether a commercial endeavor is even feasible. The industry has been extremely focused on developing new and improved catalyst systems. Some have focused on designing the catalyst systems to produce new polymers, others on improving operability, and many more on improving catalyst productivity. The productivity of a catalyst usually is the key economic factor that can make or break a new commercial development in the polyolefin industry.
Multi-modal polymers produced using multiple different catalyst types—bimetallic, trimetallic, quadrimetallic catalysts, and the like—are of increasing interest, especially in producing polyethylene and other polyolefins. Improving catalyst productivity also is of concern here, as productivity should be as high as possible in order to optimize the economic efficiency of the process, given the significant cost of multiple transition metal catalysts.
Another aspect of polyolefin production pertains to the level of gels (e.g., visible imperfections) present in the polymer products. Polymer products, especially films, that are produced with a high gel concentration may have limited or no commercial value due to, inter alia, poor aesthetics, bubble stability, or continuity. Accordingly, minimizing the concentration of gels in the polymer product—especially gels of such size as to be visually perceptible—is of great importance.